How closely do you look at your phone bill? You may be being charged for things you didn't authorize

(WXYZ) - A new form of an old scam is rearing its ugly head. It's called cramming. Consumer Reports says it could be happening right under your nose and costing you money. It works like this: Unscrupulous third parties charge fees to your phone bill for services you never authorized.

Companies other than your phone company are allowed to put charges on your phone bill for things like voicemail service or a directory listing. The trouble is that charges you didn't authorize can be slipped on your bill. The Federal Trade Commission had more than 3,000 complaints of cramming last year.

Consumer Reports says there's a big problem because with so many separate companies involved in the billing, it's tough to get any of them to take responsibility for unauthorized charges.

Consumer Reports recommends protecting yourself against cramming before it happens. Ask your phone company to put a cramming block on your account. That will immediately stop other companies from placing charges on your bill. You should not be charged for a cramming block.

Go over your bill each month with a fine-tooth comb. If you spot an unauthorized charge, demand a refund from your phone company. And report your complaint to the Federal Trade Commission .

For more information from the Federal Trade Commission about cramming, what to look for and how to prevent it, click here.